Migration of an exciton in organic polymers driven by a nonuniform internal electric field |
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| Affiliation: | 1. Department of New Material Chemistry, Korea University, Sejong, 339-700, Republic of Korea;2. Department of Chemistry, Korea National University of Education, Chungbuk, 363-791, Republic of Korea;3. Department of Electronics and Communication, LNMIIT, Jaipur, India;4. Department of Physics, LNMIIT, Jaipur, India;5. JEC Group of Colleges, Jaipur Engineering College, Kukas, Jaipur, India;1. Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India;2. Centre of Excellence in Nanoelectronics, Indian Institute of Technology Bombay, Mumbai 400076, India;3. National Centre for Photovoltaic Research and Education, Indian Institute of Technology Bombay, Mumbai 400076, India;4. National Centre of Excellence in Technologies for Internal Security, Indian Institute of Technology Bombay, Mumbai 400076, India;1. Instituto de Ciencia Molecular (ICMOL), Universidad de Valencia, Calle Catedrático José Beltrán, 2, 46980 Paterna, Spain;2. Skolkovo Institute of Science and Technology, 143025 Skolkovo, Moscow Region, Russia;3. Canatu Oy, Konalankuja 5, FI-00390, Helsinki Finland;4. Department of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI-00076 Aalto, Finland;5. St. Petersburg Polytechnic University, 195251, St. Petersburg, Russia;1. Department of Chemistry, Chemistry Institute for Functional Materials, Pusan National University, Busan 690-735, Republic of Korea;2. Department of Physics, Pukyong National University, Busan 608-737, Republic of Korea;3. Department of Physics, Ulsan University, Ulsan 680-749, Republic of Korea;4. Department of Industrial Chemistry, Pukyong National University, Busan 608-739, Republic of Korea |
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| Abstract: | 
Migration of excitons is of vital importance for the photovoltaic process in polymer-based donor/acceptor (D/A) photovoltaic system. Due to the existence of some trapping charges as well as the mismatch of energy levels at the D/A heterointerface, there will exist a nonuniform internal electric field, which may induce the migration or dissociation of an exciton or charge transfer state generated near the interface. In this work, by choosing the nonuniform internal electric field as a linear gradient form, we theoretically simulate the migration dynamics of an exciton in a polymer. It is found that the exciton will be polarized under the electric field. Especially, the polarized positive and negative charges in the exciton lie in different electric fields, which will induce a net force driving the exciton to migrate. Effects of some factors, such as the electron-phonon (e-ph) coupling, on the exciton migration are analyzed. This research reveals a new exciton migration mechanism in polymer-based D/A photovoltaic system, which might be timely for further understanding their photovoltaic process, and thus provide a new strategy to optimize the photovoltaic efficiency of the devices. |
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| Keywords: | Polymer photovoltaic devices Exciton migration Nonuniform electric fields |
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